1. Field Of The Invention
This invention relates in general to certain new and useful improvements in weightlifting machines. More particularly, the invention relates to a vertical weight array mechanism permitting user selection of a variable weight resistance throughout the movement of an exercise repetition, and the selection of weight engaging positions throughout the movement of an exercise repetition.
2. Brief Description Of The Prior Art
In recent years, weightlifting has been accepted as a method of enhancing athletic performance. A large number of weightlifting apparatus have been introduced whose function is either multiple or single exercise specialization. In most constructions, the weightlifting apparatus comprises an upstanding frame, a vertical array of weights which may be selectively introduced, and a cable or other appropriate lifting means secured to the vertical array of weights for initiating a vertical lift movement of the weights. The user of the apparatus engages the lifting means and attempts to lift the selectively introduced weights. The weight load is constant throughout the course of any repetition. While many of these apparatuses have been effective in enabling one to increase muscular size and strength, considerable time and effort can be expended to develop a given muscle throughout its complete range of movement.
Each human body is different. Particularly, no skeletal configuration has like bones of equal length. Thus, the skeletal (or lever) angles are different between bodies. Since skeletal angles also vary during performance of an exercise repetition, appropriate weight load selection is necessary to accommodate each variation in this angular leverage. A static weight load apparatus is inappropriate for such purposes.
U.S. Pat. No. Re. 31,170 discloses a method of progressive resistance wherein the resistance generated by a selected static weight load increases during the performance of an exercise. Stacked weights are manipulated by the user through a lever arm. The lever arm is pivoted to a frame, and passes through a yoke in a lift rod. A roller mounted on the yoke is carried on the upper surface of the lever arm. As the lever arm is raised, the roller on the lift rod moves on the lever arm to restrict the user's mechanical advantage and increase his effective load. The nonlinear path enables the device to progressively increase resistance throughout the exercise. A drawback of this device is that the nonlinear path is predetermined. The device cannot be adjusted to account for varying skeletal configurations. Thus, it suffers from the same disadvantage of other prior art progressive weight resistance mechanisms, namely an inability to account for varying skeletal configurations.
U.S. Pat. Nos. 3,858,873, 3,912,261, 4,200,279, 4,311,305, and 4,387,893 disclose progressive resistance weightlifting mechanisms. By introducing a cammed pulley in the lifting means, increased resistance during the performance of each repetition is experienced.
Although the inventions of the aforementioned patents are innovative in providing progressive resistance throughout an exercise movement, by virtue of their construction the user encounters strict limitations due to predesigned mechanical characteristics.